This project seeks to determine the biochemical basis of the regulation of adenylate cyclase of Escherichia coli. Toward this end two lines of investigation are proceeding: 1. We are purifying the enzyme from a strain which overproduces the enzyme, and characterizing it biochemically. 2. We are isolating and characterizing mutants which increase the activity of the enzyme in vivo, and will examine the specific changes in the cell which account for these changes. By examining mutants in which activity of the enzyme remains as high in vivo as it is in vitro, we hope to help identify the regulatory interactions that control activity of the enzyme in vivo.